Bolt anchors

ABSTRACT

An anchor device for attachment within a borehole in rock or the like comprising: a cylindrical member adapted to be received in said hole; at least one longitudinal slot in said cylindrical member and a cam surface associated with said slot; rock gripping means within said slot having a biting edge and a curved surface, generally opposite said biting edge, in engagement with said cam surface and both movable and rollable along said cam surface, and means within said slot for activating said rock gripping means, so that at least a portion of said rock gripping means, as it pivots, including said biting edge, is forced out of said slot and into the sides of said borehole in securing said device in said borehole, said activating means being resilient and compressible by said rock gripping means as said member is moved into said borehole and such compression tending to cause said biting edge to move into said rock to assist said rock gripping means to be moved into said rock by moving along and turning on said cam surface.

United States Patent 1 13,ss2,2ss

[ 72] inventor Clifford C. Wamer FOREIGN PATENTS Albion Dem", 80220371.242 9/1963 Switzerland 85/63 12 1 Appl- No 477345 206,202 12/1954Australia 85/79 1 21 Filed y 2 3 1,056,363 10/1953 France 85/79 Patentean. 1 I 1 Continuation-impart of application Ser. No. OTHER REFERENCES 1298,922,July 31, 1963, now abandoned. Camset Publicatlon dated 1964 copyalready In applicat1on with paper No. 25

Primary Examiner-Marion Parsons, Jr. [5 1 BOLT ANCHORS Anorney- VanValkenburgh and Lowe 11 Claims, 20 Drawing Figs. [52} US. Cl 85/66,ABSTRACT: An andmr d i f attachment i hi a 85/79 borehole in rock or thelike comprising: a cylindrical member [51] Int. Cl Fl6b 13/10 adapted tobe received in said hole; at least one longitudinal Field of Search /79,3, Slot in said cylindrical member and a cam Surface associated 79;285N041 with said slot; rock gripping means within said slot having abitin ed e and a curved surface, generally opposite said bit- [56]References cued ing e ige. in engagement with said cam surface and bothmova- UNITED STATES PATENTS ble and rollable along said cam surface, andmeans within said 3, 8 H1 9 Gru el al 85/3 slot for activating said rockgripping means, so that at least a 571,279 1 H1896 McKain 85/79 portionof said rock gripping means, as it pivots, including said 843,271 2/1907Hanlon 85/66 biting edge, is forced out of said slot and into the sidesof said 1.407999 2/1922 Harris 85/79 borehole in securing said device insaid borehole, said activat- 1,928.821 10/1933 Santiago. 285/105 ingmeans being resilient and compressible by said rock 2,473,046 6/1949Adams 285/104 gripping means as said member is moved into said borehole2,508,914 5/1950 Graham... 285/105 and such compression tending to causesaid bitingedge to 2,560.525 7/ 1951 Nyl 85/79 moveinto said rock toassist said rock gripping means to be 3,107,569 10/1963 Lerick 85/79moved into said rock by moving along and turning on said cam 414,09210/1889 Thurmond et a1. 85/79 surface.

5s 67 68 52 5s 63 e1 cs5v a 48 eo PATENTEU JAN 5 I97! SHEET 1 (IF '4INVENTOP fford C. Warner Fig. 5

A TTORNEYS PATENTEU JAN 5197! $552,258

SHEET 2 OF 4 INVENTOR. CL/FFORD C. WARNER Z M WWWJ 130% ATTORNEYS IPATENTED JAN 51971 3552.258

SHEET '3 OF 4 I 44 R 58 3637 43 Bu Fig. /0

INVENTOR. Clifford C. Warner ywym zwfifl A TTORNE YS BOLT ANCI-IORS Thisapplication is a continuation-in-part of my prior application Ser. No.298,922, filed Jul. 31, 1963, now abandoned.

This invention relates to bolt anchors, and more particularly to rockbolt anchors and integral bolt anchors for use in concrete, shale, hardrock or similar type of material.

In recent years, it has been the practice in the mining industry toattach steel plates to the walls and roofs of mine tunnels, stopes,drifts, etc., by means of anchor bolts to eliminate the necessity oftimbering. This is done by drilling through the loose rock into solidrock so that one end of an anchor bolt may be imbedded in the solid rockand a steel plate held against the loose rock by the outer end of thebolt. Therefore, it is sometimes necessary to drill a hole many feetdeep before solid rock is reached which is suitable for anchoring thebolt, These holes may be feet 'or more in depth. Thus, the problem isencountered of inserting'an anchor into a deep hole and then expandingit so thatit islocked in the hole to securely fasten the end of the boltin the rock. Also, a mat of rod or cable may be used to hold loose rockand it may be necessary to pull the mat toward the solid rock forseveral inches to a foot or more before the loose rock is sufficientlytight. This requires that the bolt beable to move through the anchor forthe distance necessary to tighten the mat and that hole, rather than atthe end or bottom. Thedifficulty of providing such an anchor isincreasedbecause the bolt, in someinstallations, will be under a tensionof several thousand pounds. Various types of bolt anchors and integralbolt anchors have'been developed, but none have been entirelysatisfactory; Some of these devices rely on springs to actuate wedges,but the springs do not always function properly and such anchors are notreliable. Other devices are so complicated as to make their priceprohibitive.

For construction purposes, a short anchor which is readily installed inand will provide an effective anchor in somewhat softer material, suchas concrete, is desirable. The extent of penetration of a wedge or thelike i'nto concrete is normally greater than into hard rock, whichintroduces the problem of adequate bearing area. Also, in certainoperations, it is desired to install a bolt anchor in a hole in softrock, such as shale, which requires that the area of the portion of theanchor extending into the soft rock be considerable.

Among the objects of this invention are to provide a novel rock boltanchor; toprovide such a rock bolt anchor which utilizes one or moreoutwardly rotatable wedges or cams for anchoring the bolt in rock orconcrete; to provide such a rock bolt anchor, in one embodiment, whereina single cam has wings, each adapted to slide up an inclined plane toengage the rock; to provide such a rock bolt anchor in which the boltmay be turned through the anchor for several inches to a foot or more,if desired; to provide such a rock bolt anchor, in other embodiments,wherein a plurality of cams are adapted to roll up an inclined plane toengage the rock; to provide such a wardly into the rock as theymove-along a cam surface; to provide such an integral bolt anchor inwhich the rollers are urged along the cam surfaces by a resilient block;to provide such an integral bolt anchor which may be provided withrollers of varying sizes; and to provide such integral bolt anchorsprovided with a flexible wrapper to hold the parts in place before use.

Additional objects and the novel features will become apparent from thedescription which follows, taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a top plan view of a hard rock bolt anchor of this invention,particularly adapted to be tightened over a considerable distance;

FIG. 2 is a longitudinal section, taken along line 2-2 of FIG. 1,showing the. position of a cam wedge and a paper wrapper holding thewedge in place, priorto use, the wrapper being shown in dotted lines inFIG. 1;

FIG. 3 is a perspective view of the cam of the rock bolt anchor of FIG.1;

FIG. 4 is a side elevation, partly in longitudinal section similar toFIG. 2, but showing the bolt in position in a borehole in rock, with thecam wedge initially biting into the rock, the wrapper being slipped offthe anchor as the anchor is slipped into the hole;

FIG. 5 is a longitudinal section, similar to FIG. 4, but showing thebolt position in the borehole in rock, and the cam wedge forced into therock, with a resilient plug, as in the form of a ball, shown in dottedlines after passage out of the anchor;

FIG. 6 is a top plan view of an integral rock bolt anchor of thisinvention, particularly adapted for use in softer rock;

FIG. 7 is a longitudinal section, taken along line 7-7 of FIG. 6,showing wedges in closed position with a rubber block compressed, theparts being held in place by a wrapper;

FIG. 8 is a longitudinal section, similar to FIG. 7, but showing thebolt in a hole in a softer rock or concrete wall, with the rock boltanchor wherein a pair of cams move outwardly in opposite directions intothe rocker concrete; to provide such a rock bolt anchor wherein a pairof cams or wedges roll against each other as the move outwardly; toprovide such a rock bolt anchor wherein the pair of wedges pivot withina slot in a sleeve; to provide such a rock bolt anchor having cam meansfor forcing the wedges apart as a bolt is tightened into the anchor; toprovide such a bolt anchorwhich is capable of expansion up to double itssize; to provide such a bolt anchor having a wrapper to hold the partsin place before use; to provide, in an alternative embodiment, anintegral bolt anchor; to provide such an integral bolt anchor havingwedges which are pivoted outwardly into the rock by rollers which moveoutwedges partially open, the wrapper being removed when the anchor isinserted in the hole;

FIG. 9 is a longitudinal section, similar to FIG. 8, but showing thewedges fully extended.

FIG. 10. is a longitudinal section of an alternative, integral blotanchor which is of smaller size and utilizes a rolling cam, beingparticularly adapted for use in concrete;

FIG. 11 is a transverse section, on an enlarged scale and taken alongline 11-11 of FIG. 10;

FIG. 12. is a transverse section, on an enlarged scale and taken alongline 12-12 of FIG. 10;

FIG. 13 is a longitudinal section, similar to FIG. 10, but showing theintegral bolt anchor in position in a hole in a concrete wall, with thecam biting into the concrete;

FIG. 14 is a longitudinal section, similar to FIG. 13, but showing thecam forced further into the concrete;

FIG. 15 is a transverse section, taken along line 15-15 of FIG. 14;

FIG. 16 is a top plan view of a further alternative bolt anchor,particularly adapted for use in hard rock;

FIG. 17 is a longitudinal section, taken along line 17-17 of FIG. 16,showing also a paper wrapper which holds the parts in place prior touse;

FIG. 18 is a perspective view, on an enlarged scale, of the cam of thebolt anchor of FIG. 16;

FIG. 19 is a longitudinal section, similar to FIG. 17, but showing therock bolt anchor in position in a hole in rock, with the cam biting intothe rock; and

FIG. 20 is a longitudinal section similar to FIG. 19, but showing thecam forced outwardly further into the rock.

In accordance with this invention, a rock bolt anchor is provided, as inFIGS. 1-5, which includes a cylinder C adapted to receive a cam wedge Whaving wings 10 and 11 for sliding movement along laterally rounded,longitudinal cam edges 12 and 13 of an opening into a bore 14 ofcylinder C. The outer end 15 of bore 14 is provided with threads, asshown, which engage threads 16 of a bolt 17 having a head 18, such ashexagonal, while the outer end 19 of the bore need not be threaded buthas a larger'diameter than theinner end, such bolt 17 of FIGS. 1 and 2,which, of course, may otherwise be several feet in length, as on theorder of up to 15 feet, but when the bolt is to be tightened for aconsiderable distance, in order to draw a mat against loose rock,for.instance, the threads may extend for several feet, as in the caseofthreads 16' of bolt 17' of FIGS. 4 AND 5.

Cam wedge W is also provided with flat sides 21, and 22, extending fromthe inner end of wings l and ll, respectively, and spaced apartadistance slightly less than the distance between cam edges 12 and l3,so that the inner end of cam wedge ,W may be deflected into the bore.Top 23 of cam wedge W and the outer surfaces of wings and 11 arelaterally arcuate to correspond to the outer diameter of sleeve {8,while the underside 24 of each wing ,10 and 11 as in FlG. 3,.islaterally concave to correspond to the lateral convexity of cam edges12 and 13, to prevent cam wedge .W from twisting as it rides up onto camedges 12 and 13. The front face 25 thereof is inclined downwardly andforwardly, :so that a I dihedral angle will be formed at the biting edge26, since a square corner may tend to break off under extreme pressure,The depth of wings l0 and 11 is such that the outer surface of the camwedge will form a circle with the outer surface of sleeve S, when thewings rest in the lowest point of cam edges 12 and 13, asin FIGS. 1 and2, while ball ispreferably slightly greater in diameter than the boltandwill be compressed by the cam wedge W. The underside 27 of thelatteris transversely concave and slopes upwardly from front to rear, for apurpose described later.

Prior-to installation, the cylinder C is enclosed by a cylindricalwrapper sleeve ,28, conveniently formed of cardboard, which holdsthe'parts in the positionof FIG. ,2 and is slipped onto or removed fromthe cylinder C in the direction of arrow 29, since the inside of wrappersleeve 28 will slip along .the outer surface ofcam wedge'W and pastbiting edge 26, causing the cam'wedge to compress ball 20. Thus,.wrappercan slip over the'biting edge 26 if moved in'the direction ofarrow29,-but if moved in the reverse direction, ie in the direction of dottedarrow 30, the biting edge 26 will'bite into the inside ofzthe wrapper,through the pressure of ball 20 and will cause the inner edge of camwedge W to tip into ,the bore 14,

preventing further movement of the wrapper. This action of I the wrapperillustrates what happens when the bolt anchoris cam wedge W further intothe rock, so that furtl'rer tightening of the bolt will draw the mattoward the solid rocklrather than tighten the anchor."Normally, arelatively short moverrl ent of cylinder C will suffice to lock theanchor sot hal ajrnat oi the like-will begin to be tightened,withmalletfigmen ng rihe bolt causing movementof the mat pr plategormovement of "the cylinder-C, or both, with theQfinaI-i'estiltthat ,thecam wedge W will be pushed laterally greater force is nece ssaryito movecylinder Cjn the holethanto tighten the rn'zit. When a mator thelikeisrmoved severalnches}ihe-bolt 17' of FIG. Swill pushxthe ballltlthrough end 311?: of the bore, as to the dotted position of FIG. 5rid beyond,;the ball being followedby the inner end' of th efbolt, Asthelball; is pushed past thecam wedge W, the outer surfa'e e of'the camedge cannot become parallel tothe bore, sincethe taper between top 23and underside,24, accommodates movementof the ball,-while as camedges'lZ and 13 slide under wings l0 and 11, respectively, the cam wedge.W is pushed further out into the rock. Thus,the.ca m wedge will alwaysbe tippedinto .the rock.

Since as cam wedge-W, is moved into the rock, the reaction is on theopposite side of cylinder C, the latter may, on the underside and atthe'inner end, beprovided with ttansverse serrations or ,teeth 33lforgripping the rock in that area, particularly as .the cam wedgeapproachesa positio'n furtherto the rear ofthe cylinder; r v

An alternative embodiment is shownin FIGS. e 9,,wh e rein an integralbolt anchor B is provided for use in a hole of the same size as thebolt,such as hole 46 in a rock wall] 47 of FlGS. 8.and;9. Bolt B has-threads48 at one end for receiving a put}? for attaching a metal plate, such asplatesSO offlGSQB'and 9. to .wall 47, as is more-fully described below,and a slot-'51. ad- .jacent the other end which is adapted to receivecamyv edges 52 and 53 Cam -wedges 52and53 are provided witht'cur-vedinner surfaces 54 and 55, respeetively, which engage and roll againsteach other during extension of the wedges. The wedges also have flatouter surfaces 56 and 157; respectively, and rounded rearends 58 and 59which are adapted to slide against the curved surface'60 at the end ofslot 511 during expansion. The opposite ends'of cams 5-2Jahd 53 aieforjeed into the rock by rollers 61 and '62 which may'have smoothsurfaces or be'knurled and are urged outwardly along-caln surfaces 63 rand 64, respectivelyfby a resilient block 65, as of latexrubber,

installed. Thus, when the bolt anchor is installed, the wrapper 28 isslipped off sleeve 5 and onto the bolt as the anchor is inserted in aborehole ,31 in rock ,32, which borehole has a diameter slightly inexcess of cylinder C. The bolt 17 or 17' is sufficiently long thatcylinder C may be pushed into the hole until head 18 of the bolt engagesthe hole collar or the plate, mat or other part to be held in position.As in the case of wrapper-sleeve 28, the anchor may be pushed inwardlyin the hole as far as desired, since although ball 20 will push camwedge W against the inside of the hole, the cam wedge will readily slidealong the inside of the hole, in a position corresponding to FIG. 2.When the desired position is reached, tightening of the bolt is begun,as by turning head 18 with an appropriate wrench, but as soon as aslight return movement is imparted to cylinder C, biting edge 26 willengage the rock and the inner end of cam wedge W will deflect into bore14, as in FIG. 4. Continued tightening of the bolt will move thecylinder C outwardly in the hole, with ball 20 being pushed inwardly inthe cylinder and being compressed by the cam wedge W. As long ascylinder C is moved in the hole, cam edges 12 and 13 will slide underWings 10 and 11, respectively, forcing cam wedge W outwardly into therock, with increasing resistance to movement of cylinder C, as to theposition of FIG. 5. Of course. if a mat or the like is being pulledagainst loose rock, the anchor bolt will usually reach a point ofequilibrium where the force necessary to draw the mat toward the solidrock will be less than the force necessary to force at the inner endofslot15 l. Conveniently, block has a central transverse slot 66 tofacilitate displacement thereof, although this slot isinot absolutelynecessany. it will be ,evident that -other resilient ,material, such asplastic or spring metal may be used, but rubber has been found to be themost satisfactory. v i I e ;Prior to .use,t he parts are held in place,as shown in FIG. 7, by a paper or cellophane wrapper 67. Thus, integralbolt anchor B, together with wrapper 67 maybe inserted in hole 46drilled in rock 47 and nut'49 tightened against plate '50, While wrapper67 is tight-enough to hold .the parts in place, it is loose enough toallow rubber block 65 to push rollers 61 and against the sides of thehole, Also, when the bolt is driven in the hole, most of the wrapperwill be torn off by the sides'of the hole. Of course, the sides of thehole will contain the rollers 'after the bolt is inserted therein. Thus,the'integral bolt anchor can be inserted in the hole without diffieulty,because the sides of the hole will merely force rollers 61 and 62 intorubberblock 65. However, as nut 49 continues to be tightened and bolt'Btends to be pulled back out of the hole, rbllers 6i and 62 will beforced outwardly along cam surfaces63 and '64 by rubber block 65, sothat they engage the side s'o'f the hole, as in H0. 8, forcing the endsof wedges 5 2 and33 out into the rock also. The only purpose of therollers is to activate the wedges. Therefore, once the ends of thewedges move outwardly beyond the rollers, th e rollers become inactiveand .no

longer perform any function. Initially, however, they serve as a thewedges to prevent jamming. It will be understood that, if bolt B is tobe used in rock having a wide variance in compressive strength, wedges52 and 53 may be provided with interengaging gear teeth, so thatsimultaneous movement of the wedges will be assured. I 1

Once rounded. ends 58 and 59 come together, they become the fulcrumfor'the wedges, so that a large mechanical advantage is obtained as nut49 continues to be tightened against plate 50, forcing the ends of thewedges into the rock. If the rock is relatively soft, theoretically thenut may be tightened until the wedges are-perpendicular to the axis ofbolt B, as in FIG. 9, so that notches 68 and 69 engage the ends ofcurved surface 60, as shown. When the wedges 52 and 53 reach theposition of FIG.9, the front surfaces thereof will provide a maximumbearing area against the anchor pulling out of the softer rock, whilethe area of flat surfaces 56 and 57 will also bear against the rock toprevent the wedges from rotating from the perpendicular position shown.

An alternative embodiment, particularly adapted for use in concrete. isshown in FIGS. l015, wherein a smaller integral bolt anchor B" isprovided at its inner-end with a slot 35 having a curved base, as shown,the outer end being provided with threads 70. A cam roller R has abiting edge 36, with a planar surface 37 extending therefrom at one sideand a concave surface 38 at the opposite side, a generally. arcuatesurface 39 adjoining planar surface 37 and a convex knob 40, such asgenerally semicircular, merging with concave surface 38, with a notch 41between knob 40 and surface 39, which may be filled, if desired, toprovide a flat area. Cam roller R is located in slot 35, with bitingedge 36 and the adjacent portion of cam roller R initially extendingabove bolt B" and held in place, prior to installation, by a breakablewrapper 42, as in FIG. 11 conveniently formed oftape provided with anadhesive on one side. An elongated, generally triangular, resilientblock 43, as of rubber, is placed at the outer end of slot 35 and may beheld in place by crimps 44 on opposite sides and at the edges of slot35, as in FIG. 12. Upon insertionofbolt B in a hole 74 in concrete 73,as by tapping, the exposed surface of cam roller R will cause the camroller to be tipped into slot, breakingthe tape and providing sufficientpressure to force it downwardly and forwardly into slot 35 and againstblock 43 to compress the block, but without edge 36 biting into theconcrete Upon tightening nut 71 on threads 71), as against an angle 45or other part to be attached to the concrete wall, thereby reversing thedirection of movement of the bolt, the biting edge 36 of cam roller Rwill be urgedinto the concrete by the pressure of block 43, as in FIG.13. Further tightening of nut 71 will cause cam roller R to rock ontothe base of the slot, with the surfaces on opposite sides of notch 41engaging the slot base. The cam roller R may then slide upwardly alongthe base of the slot, in such position, or may roll further up theincline of slot 35, as to the position of FIG. 14 depending upon theease with which the cam ro'ller'is forced into the concrete. Thus, ifbiting edge 36 encounters a harder and larger piece of aggregate in theconcrete, requiring a greater force to push the cam roller into it, asliding action is more likely, while if biting edge 36 engages smallerpieces of aggregate or a space between two harder and larger pieces ofaggregate, the rolling action is more likely, the latter being morelikely during normal use. Further rotation of cam roller, R, from theposition of FIG. 14, will be hindered by the concave surface 38. Thus,an integral anchor bolt is provided which is of simple construction butcan expand to about twice its original diameter, as in FIG. 15.

The embodiment of FIGS. 16-20 is particularly adapted to be used as aroof bolt anchor in softer rock and is similar in many respects to theconcrete bolt anchor of FIGS. -15 but is larger in size and includes acylinder.C having a slot 85 provided with a base which is inclineddownwardly from the rear toward the front and communicating with athreaded bore 86 adapted to receive the threads 16 of a bolt 17 having ahead 18, similar to the bolt of FIG. '1'. The cam roller R is similar tothe cam roller R of FIGLIO; except for size, being shown in FIG. 18 in aposition reversed from that of FIGS. 21, 23 and 24 for clarity ofillustration. Thus, as in FIG. 18, cam roller R is provided with abiting edge 36, a planar surface 37, a concave surface 38, an arcuatesurface 39, a knob 40 and a notch 41. In this instance, the resilientblock is a cylindrical plug 87 adapted to be compressed into bore 86 toretain it in place initially. Cylinder C may also be provided withtransverse serrations 33 at the inner end on the side opposite slot 85,for the same purpose as serrations 33 of FIG. 2. Cam roller R may alsobe held in place, for transportation and handling, by a sleeve 28 ofcardboard or the like, which may be slipped onto cylinder C from theinner end and off at the outer end, onto bolt 17, in the same manner assleeve 28 of FIG. 2. Plug 87 has a length such that cam roller R willextend beyond the periphery of cylinder C, unless forced down into slot85 to compress the plug, while sleeve 28' is conveniently slipped offonto bolt 17 as cylinder C is slipped into a borehole 31' in rock 32.When cylinder C reaches the desired position, and bolt 17 is initiallyturned, the pressure of plug 87 will cause biting edge 36 to bite intothe rock, as in FIG. 19. Tightening of bolt 17, as against a plate 88 tobe held against the rock, as of the roof of a tunnel, will compress plug87 against cam roller R and withdraw cylinder C' causing cam roller R toroll about arcuate surface 39 until knob 40 engages the base of slot 85,as in FIG. 20. In slightly harder rock, the device will be anchoredsecurely in this position, but if the resistance to turning of bolt 17indicates that cam roller R should be forced further into the rock, suchas softer rock, the bolt 17 may be further tightened. Depending upon theresistance of the rock to penetration by the cam roller R, the camroller will, from the position of FIG. 20, either slide up the inclinedbase of slot 85, retaining the relative position of FIG. 24, or willrock about knob 40 and rotate further into the rock, as to a positioncorresponding to the position of cam roller R in FIG. 14. As will beevident, this embodiment provides a rock bolt anchor which willaccommodate various degrees of hardness of the rock and can be expandedto correspond thereto.

Although several embodiments of this invention have been illustrated anddescribed, it will be understood that other embodiments may exist, thatvarious features of one embodiment may be incorporated in otherembodiments and that various changes may be made in each embodiment,without departing from the spirit and scope of this invention.

Iclaim: 1. An anchor device for attachment within a borehole in rock orthe like comprising:

a cylindrical member adapted to be received in said hole. at least onelongitudinal slot in said cylindrical member and a cam surfaceassociated with said slot; rock gripping means within said slot, havinga biting edge and a curved surface, generally opposite said biting edge,in engagement with said cam surface and both movable and rollable alongsaid cam surface; means within said slot for activating said rockgripping means, so that at least a portion of said rock gripping means,as it pivots, including said biting edge, is forced out of said slot andinto the sides of said borehole in securing said device in saidborehole, said activating means being resilient and compressible by saidrock gripping means as said member is moved into said borehole; and suchcompression tending to cause said biting edge to move into said rock toassist said rock gripping means to be moved into said rock by movingalong and turning on said cam surface. 2. An anchor device, as set forthin claim 1, wherein said rock gripping means is provided with a wing ateach side having a curved surface and a cam surface is located at eachside of said slot in position for engagement with said curved surface ofthe corresponding wing said slot,

3. -An anchor device, as set forth in claim I, wherein said slot iscovered with a wrapperfor holding said rock gripping means within saidslot before insertion of said device into said hole.

4. An anchor device, as set forth in claim I, wherein:

. normally aligned with the outer surface of said member;

and 7 said cam surface is formed at the inner end of said slot forengagement by a curved end of each said wedge opposite said biting edge.

5. An anchor device, as set forth in claim 1, wherein:

said cam surface associated with said slot comprises an inclined edge ateach side of said slot; and

said rock gripping means comprises a can wedge disposed in said slot andhaving a wing at each side engaging the respective inclined edge.

6. An anchor device as set forth in claim 5,wherein said resilient meansis a ball formed of rubber-like material.

7. A anchor device, as set forth in claim 5, wherein the inside of saidcam wedge is softer arcuate.

a cylindrical top having a lateral curvature corresponding to that ofsaid member, the outer surface of said wings being a continuation ofsaid top;

a transverse front face inclined at an angle away from a perpendicularto said top; 1

a transversely arcuate underside longitudinally inclined towards saidtop in a direction away from said front face; and

.the underside of each wing is transversely concave to fit againsttransversely convex surfaces of said inclined edges.

10. A bolt anchor adapted for use within a borehole in a rock orconcrete wall, comprising:

a cylindrical member having a longitudinal slot extending from a pointat least adjacent the inner 'end toward the opposite end, said slothaving a base inclined from said inner end to a greater depth at a pointspaced therefrom;

8 "a cam roller withinsaid slot having a transverse biting edge and agenerally arcuate convex surface opposite said 'biting edge adapted toroll along said ihclined base of "said slot; said cam roller having aconcave surfac'e'on one sideof said biting edge anda planar surface-ohthe opposite side of said biting edge, said generally arcuate surface'adjoinin'g said planar surface; V It -:1. said cam roller also havingagenerally semicircular-Arno!) havinga radius less thansaid generallyarcuate surface. said knob merging'at one side with said cohcave surfaceand at the other side forming iLfi'lOlCh adjoining ,said

generally arcuate surface; r, t resilient means in the deeper portion ofaid slot which is compressed by said cam roller uponmovement ofsaidmember into said borehole and which causessaid biting edge to engagesaid rock whenever said membe r is moved outwardly said borehole; and v1 means for moving said member outwardly in saidiborehole.

11. An integral .bolt anchoradapted for use within a hole in a concretewall, comprising:

a bolt threaded-at its outer end for receiving a nut and having alongitudinal slot adjacent the inner end thereof, said slot havingaconcavebase;

a cam roller adapted to roll along said base and having a generallyarcuate convex surface resting at one point on said inclined base, aplanar surface at the front and above said generally arcuate surface, aconcave surface'on the top and a generally semicircular knob at theupperrear having a lesser radius than said genera'llyarcuate surface,said planar. surface and said concave surface intersecting at a frontupperbiting ed eand said knob forming a notch on the underside at t 6rear edge of said generally arcuate surface; and z s t u a resilientblock having a generally triangular s'hapewiththe larger end abuttingsaid cam roller in said slot and .being compressed by saidcam roller assaid bolt is moved into said hole and causing sa'id biting'edge to biteinto the concrete when said boltis moved outwardly in said hole, saidgenerally arcuate surface rolling along saidvslotbase as said bolt ismoved further outwardly in said hole until said knob also engages saidbase. i a

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 552,258 Dated January 5 1971 Inventor) Clifford C. Warner It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 42 "blot" should read bolt Column 7 line 13, "can" shouldread cam line 19, "softer" should read transversely Signed and sealedthis 25th day of May 1971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, J Attesting OfficerCommissioner of Patent l FORM F'O-1050 (10-69) USCOMM-DC 5037s.

1. An anchor device for attachment within a borehole in rock or the likecomprising: a cylindrical member adapted to be received in said hole. atleast one longitudinal slot in said cylindrical member and a cam surfaceassociated with said slot; rock gripping means within said slot, havinga biting edge and a curved surface, generally opposite said biting edge,in engagement with said cam surface and both movable and rollable alongsaid cam surface; means within said slot for activating said rockgripping means, so that at least a portion of said rock gripping means,as it pivots, including said biting edge, is forced out of said slot andinto the sides of said borehole in securing said device in saidborehole, said activating means being resilient and compressible by saidrock gripping means as said member is moved into said borehole; and suchcompression tending to cause said biting edge to move into said rock toassist said rock gripping means to be moved into said rock by movingalong and turning on said cam surface.
 2. An anchor device, as set forthin claim 1, wherein said rock gripping means is provided with a wing ateach side having a curved surface and a cam surface is located at eachside of said slot in position for engagement with said curved surface ofthe corresponding wing said slot.
 3. An anchor device, as set forth inclaim 1, wherein said slot is covered with a wrapper for holding saidrock gripping means within said slot before insertion of said deviceinto said hole.
 4. An anchor device, as set forth in claim 1, wherein:said rock gripping means comprises a pair of wedges mounted within saidslot, said slot extending through said member and said wedges havingengaging longitudinally curved inner edges and longitudinally straightouter edges normally aligned with the outer surface of said member; andsaid cam surface is formed at the inner end of said slot for engagementby a curved end of each said wedge opposite said biting edge.
 5. Ananchor device, as set forth in claim 1, wherein: said cam surfaceassociated with said slot comprises an inclined edge at each side ofsaid slot; and said rock gripping means comprises a can wedge disposedin said slot and having a wing at each side engaging the respectiveinclined edge.
 6. An anchor device as set forth in claim 5, wherein saidresilient means is a ball formed of rubber-like material.
 7. A anchordevice, as set forth in claim 5, wherein the inside of said cam wedge issofter arcuate.
 8. An anchor device, as set forth in claim 5, whereinthe inside and outside of said cam wedge are inclined toward each otherin a longitudinal direction away from the initial position of saidresilient means.
 9. An anchor device, as set forth in claim 5, whereinsaid cam wedge includes: a cylindrical top having a lateral curvaturecorresponding to that of said member, the outer surface of said wingsbeing a continuation of said top; a transverse front face inclined at anangle away from a perpendicular to said top; a transversely arcuateunderside longitudinally inclined towards said top in a direction awayfrom said front face; and the underside of each wing is transverselyconcave to fit against transversely convex surfaces of said inclinededges.
 10. A bolt anchor adapted for use within a borehole in a rock orconcrete wall, comprising: a cylindrical member having a longitudinalslot extending from a point at least adjacent the inner end toward theopposite end, said slot having a base inclined from said inner end to agreater depth at a point spaced therefrom; a cam roller within said slothaving a transverse biting edge and a generally arcuate convex surfaceopposite said biting edge adapted to roll along said inclined base ofsaid slot; said cam roller having a concave surface on one side of saidbiting edge and a planar surface on the opposite side of said bitingedge, said generally arcuate surface adjoining said planar surface; saidcam roller also having a generally semicircular knob having a radiusless than said generally arcuate surface, said knob merging at one sidewith said concave surface and at the other side forming a notchadjoining said generally arcuate surface; resilient means in the deeperportion of said slot which is compressed by said cam roller uponmovement of said member into said borehole and which causes said bitingedge to engage said rock whenever said member is moved outwardly saidborehole; and means for moving said member outwardly in said borehole.11. An integral bolt anchor adapted for use within a hole in a concretewall, comprising: a bolt threaded at its outer end for receiving a nutand having a longitudinal slot adjacent the inner end thereof, said slothaving a concave base; a cam roller adapted to roll along said base andhaving a generally arcuate convex surface resting at one point on saidinclined base, a planar surface at the front and above said generallyarcuate surface, a concave surface on the top and a generallysemicircular knob at the upper rear having a lesser radius than saidgenerally arcuate surface, said planar surface and said concave surfaceintersecting at a front upper biting edge and said knob forming a notchon the underside at the rear edge of said generally arcuate surface; anda resilient block having a generally triangular shape with the largerend abutting said cam roller in said slot and being compressed by saidcam roller as saId bolt is moved into said hole and causing said bitingedge to bite into the concrete when said bolt is moved outwardly in saidhole, said generally arcuate surface rolling along said slot base assaid bolt is moved further outwardly in said hole until said knob alsoengages said base.